Cavitary Melanoma of Ciliary Body Simulating a Cyst

Cystlike cavities rarely occur in uveal melanoma, and are recognized on ultrasonography as acoustically hollow regions.^1-4 In such cases, diagnostic confusion between a solid or cystic lesion can lead to delay in treatment of melanoma. We report a 42-year-old man with a ciliary body mass that simulated a large cyst ultrasonographically but was later confirmed on enucleation to be a cavitary melanoma.

A 42-year-old man had a 2-year history of decreased vision in his right eye. Following several unsuccessful refractions at a regional referral center, the patient was found to have a multicystic ciliary body mass inducing lenticular astigmatism and was referred to the Wills Eye Hospital Oncology Service (Philadelphia, Pa).

Visual acuity was 20/200 OD and 20/20 OS. The right eye had episcleral sentinel vessels inferiorly and superior subluxation of the cataractous lens. Fundus examination revealed a brown ciliochoroidal mass inferiorly, measuring 14 × 13 × 12 mm (Figure 1). On transillumination, a light shadow corresponding to the rim of the mass was found, but the mass transmitted light overall. B-scan ultrasonography revealed a multicystic lesion with the largest cyst measuring 11 mm in diameter, surrounded by a thin reflective wall and base measuring only 1.0 mm in thickness (Figure 2). The cavities occupied 90% of the lesion. Based on the solid basal component and the sentinel vessels, our diagnosis was cavitary melanoma of the ciliary body. Enucleation was performed (Figure 3).

Histopathological examination disclosed a ciliary body mass composed of spindle B malignant melanoma cells lining large intratumoral cavities. The cavities were filled with serous fluid and had no endothelial or epithelial lining (Figure 4A-C). After a 1-year follow-up, the patient was healthy without metastasis.

Cystlike cavities are uncommon in uveal melanoma. In 1 report, microscopic cavitation was found by histopathological examination in 8.4% of uveal melanomas.⁵ However, clinically visible cavitation is very rare. We were able to find only 25 reported cases of cavitary uveal melanomas (Table 1 and Table 2).

Ultrasonography is an important diagnostic tool for uveal melanoma, particularly those with cavitary changes. On ultrasonography, cavitary melanomas can manifest single or multiple cavities, sometimes with fine echoes within the cavity.^2-10 In reported cases, the mean volume of melanomas occupied by cavity was 54% (range, 30%-79%). Our case was unusual in that the cavity occupied 90% of the melanoma.

Transillumination is also an important diagnostic procedure. In the 25 reported cases, transillumination showed a shadow corresponding to the ciliary body mass.^2-10 However, in our case, transillumination showed a unique pattern with a shadow at the rim of the tumor where it was solid and transmission of light through the central cavity.

The differential diagnosis of the cavitary melanoma of the ciliary body includes iris pigment epithelial cyst, ciliary body cyst, medulloepithelioma, cystic adenoma of ciliary pigment epithelium, and ciliary body detachment.¹ Iris pigment epithelial cysts are found on the posterior iris surface, most commonly in the iridociliary sulcus, and are hollow on ultrasonography. Ciliary body cysts usually occur in the pars plana, and pars plicata cysts are extremely rare. They appear clear, not brown, and transmit light.

It has been postulated that cavitation in melanomas may result from necrosis, hemorrhage, or the accumulation of mucoproteinaceous substances or serous exudation.^5-10 The cavity is not a true cyst as there is no epithelial lining. It is speculated that an imbalance between blood supply and tumor growth leading to necrosis and tissue reabsorption could play a role in the formation of cavity.^5,6 We did not observe necrosis in our case. Similar changes can be observed in skin nevus or melanoma. In a review of 10 581 skin melanocytic nevi from a pathology laboratory, 93 (.9%) nevi were found to have cavities.¹¹

Correspondence: Dr Shields, Ocular Oncology Service, Wills Eye Hospital, 840 Walnut St, Philadelphia, PA 19107 (mvenditto@shieldsoncology.com).

Financial Disclosure: None.

Funding/Support: Support provided by the Paul Kayser International Award of Merit in Retina Research, Houston, Tex (Dr J. Shields), Macula Foundation, New York, NY (Dr C. Shields), the Noel T. and Sara L. Simmonds Endowment for Ophthalmic Pathology, Wills Eye Hospital (Dr Eagle) and the Eye Tumor Research Foundation, Philadelphia, PA (Dr C. Shields).

Previous Presentation: This report was presented at the American Association of Ophthalmic Pathology; November 15, 2003; Anaheim, Calif; and at the Eastern Ophthalmic Pathology Meeting; October 3, 2003; Durham, NC.